This compact set of step drill bits, which contains a 4-12mm, a 4-20mm, and a 3-12mm. Two-ribbed design can provide faster, smoother cutting.Note: Before starting to drill and screw, the Automatic Center Punch can be used to mark hole locations. It delivers an automatic, high-impact, spring-loaded strike when pressed against wood, metal, and plastic surfaces. An adjustable cap regulates the impact force. It features a heat-treated alloy steel punch with a sharp precision tip and a corrosion-resistant brass body with non-slip knurled grip.Vastar 3 cutters come in the following sizes:5 step drill: 4-12mm (4mm, 6mm, 8mm, 10mm, 12mm)9 step drill: 4-20mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm , 20mm)10 step drill: 3-12mm (3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm)Note:Automatic Center Punch is not available.